1. Field of the Invention
The inventions disclosed and taught herein relate generally to dual-bus static switches; and more specifically to a three-pole transfer switch system for managing neutral current.
2. Description of the Related Art
In an automatic electrical power transfer switch system, the system selectively connects, either manually or automatically, one of two independent power sources to a load. Under normal conditions, when the first power source is available, the system connects the first power source to the load. If the first power source fails, the transfer switch system will connect the second power source to the load to prevent disruption of power to the load.
Typically, each power source includes a neutral line solidly grounded to meet safety code requirements. The neutral lines are connected to a common point that provides a single neutral connection to the load. Since the neutral current must complete its path to the power source that is feeding the load, the neutral line current may split into two portions, one to each power source. This condition creates undesirable ground currents that can create ground loops in the distribution system, which can cause unwanted ground fault interrupter trips.
Applicant has invented a neutral current management system for a dual-bus static transfer switch for four-wire loads.